Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 010231 AFDAKQ Area Forecast Discussion National Weather Service Wakefield VA 1031 PM EDT THU JUN 30 2016 .SYNOPSIS... A cold front approaches from the northwest tonight as high pressure remains over the western Atlantic. The front crosses the region late Friday into Friday evening, before stalling across North Carolina through early next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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Forecast updated to bump up chance of rain over Eastern areas where areas of shras/tstms are passing thru the region this eveng. Threat of severe wx is ending, but still could see some small hail and gusty winds. Pops decrease to 20% everywhere late ovrngt with mainly dry conditions expected. Previous Discussion... Latest radar trends depict isolated to widely scattered showers developing along a dewpoint and instability gradient over central Virginia. Sea breeze convection has remained south of the Albemarle Sound thus far. Storm motion is slow in weak flow, generally to the northeast. Expect a slight uptick in coverage as a shortwave tracks across northern Virginia late this afternoon into this evening. MLCAPE progged around 1,000 J/kg North Carolina into central Virginia, with less instability noted toward the coast. Will retain chance POPs for scattered showers and thunderstorms inland. Less activity near the coast. SPC maintains a marginal risk for severe weather as inverted V soundings indicate the potential for gusty winds. Convection expected to wane this evening with the loss of daytime heating and instability. Upstream, scattered showers and thunderstorms over the central Appalachians progged to track into the Piedmont this evening. The shortwave tracking into the Piedmont along with divergence aloft expected to maintain widely scattered to scattered showers (and possibly a thunderstorm) from the Piedmont across the northern forecast area to the Delmarva through late tonight. Slight chance POPs maintained across the southeast as the wavy front kinks northward behind the northern Virginia wave. Lows in the upper 60`s to low 70`s under a partly cloudy sky.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... Potent shortwave energy digs over the eastern Great Lakes Friday and into the Saint Lawrence River Valley. Associated cold front reaches the central Appalachians Friday morning. The front doesn`t drop into the local area until late Friday, but pressure falls on the lee side of the mountains will result in added low level convergence along a thermal trough over the Piedmont. This trough, along with modest height falls and increasing winds aloft will provide the focus for scattered to possibly numerous showers and thunderstorms. Another area of low level convergence will exist along the diffuse frontal boundary in southeast Virginia and northeast North carolina. Low level return flow and 850mb temps warming to around 18C (+1 standard deviation) will push temperatures into the upper 80`s to around 90. Dewpoints warming to around 70 and precipitable waters above 1.5 inches will result in an increasingly unstable air mass. MLCAPE values climb to around 1,500 to 2,000 J/kg. However, marginal deep layer shear, limited height falls, and modest mid level lapse rates (refer to anomalous 850mb temps) will limit the overall convection potential. SPC has expected a marginal risk of severe weather into the Delmarva for gusty winds and hail, with only general thunder back into the remaining forecast area. Coverage will be best over the Delmarva, and have increased POPs to likely. Solid chance elsewhere. Front reaches the coast Friday evening with lingering scattered showers and thunderstorms expected from the Northern Neck to the Delmarva. Drying after midnight as the best moisture pushes offshore. The front stalls in the vicinity of northeast North Carolina late Friday night. Lows range from the mid 60`s northwest to mid 70`s southeast. Short term guidance continues to stall the front over North Carolina Saturday through Sunday. Deep moisture pushes south of the local area Saturday, along with the best chances for measurable precip. Will keep mention of scattered showers and thunderstorms Saturday afternoon for far southern Virginia and northeast North Carolina as moisture begins to return in low level southwest flow. Highs in the mid to upper 80`s under a partly cloudy sky north to mostly cloudy south. Front remains in the vicinity of northern North Carolina Saturday night through Sunday as several waves in the westerly flow ride along the front. Moisture also pools along the boundary with precipitable water values around 2 inches. Good storm motion may limit the overall potential for excessive rainfall Sunday, but anomalous moisture and several upper waves will likely result in periods of heavy rainfall. Highs Sunday only in the low 80`s under a mostly cloudy sky. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... A frontal boundary shifts northward through the area Sunday night into Independence Day as a trough drops into the Great Lakes and a ridge builds over the East Coast. The general consensus is for the trough to push through the region Tuesday into Tuesday night, followed by a pattern that features a weak trough off the coast, with a mid/upper ridge centered over the Southern Plains and Lower Mississippi Valley Wednesday into Thursday. The 30/12z GFS remains more amplified during the Tuesday-Thursday period than GEFS mean and 30/12z ECMWF. PoPs will generally be diurnally driven Monday and Tuesday, averaging 30-40% across the area. PoPs drop to less than 15% by Wednesday as drier air builds in from the north. A shortwave trough dropping in from the NW could trigger some afternoon/evening showers/tstms by Thursday, but confidence with respect to details is low at this range (a week in advance). Forecast high temperatures are generally in the low/mid 80s Independence Day, and then trend into the mid 80s to around 90 Tuesday through Thursday. Lows will average in the mid 60s to low 70s. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... VFR conditions expected through the forecast period (outside of convection). The lingering frontal boundary along the VA/NC border will likely be the trigger for sct convection through the early evening towards midnight. An area of showers and thunderstorms developed this evening over south central VA and has generally been moving east. The storms have lots of rain and some hail but not much wind. PHF is most likely to be affected with the chance for ORF to have some thunder and heavy rain by around 10 pm. Once this cluster ends...there should be some clearing after midnight although satellite shows clouds moving east into the WVA mountains. Some of this might spill over into central VA by morning as mid level clouds. Models differ on CIG heights tonight once the pcpn dissipates but do indicate some patchy fog late tonight. Outlook: Generally, VFR conds will prevail through much of the period. However, look for potential brief windows of diminished visibility and ceiling at all terminals in numerous showers/tstms each day in the period, mainly during the aftn/evening hours. && .MARINE... A SE wind will average aob 10kt through tonight as high pressure remains situated offshore with a trough inland. A cold front approaches from the NW Friday, which will result in a wind shift to SSW with speeds aob 15kt. The cold front drops into the area Friday evening, and pushes through later Friday night, with high pressure building into the area Saturday. A brief NNW surge is expected in the wake of the front early Saturday morning. Generally sub-SCA conditions are expected, but a brief period of wind gusts up to 20kt is possible over the Bay. The wind becomes NE and gradually diminishes Saturday. The front drops south of the area Saturday night into Sunday, and then lifts through the area Sunday night into Monday. A weak front approaches from the NW Tuesday. Seas average 2- 3ft through the period, with 1-2ft waves in the Bay. A brief period of 2-3ft waves is possible in the Bay Saturday morning with the aforementioned surge. && .CLIMATE... RIC now up to 7.81" for the month of June through 3pm today. This makes 2016 the 7th wettest June on record (2004 is wettest June with 9.93"). Also, the May-June total at RIC now stands at 17.60" and is the 2nd wettest (1972 is wettest with 17.69"). && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...SAM/TMG NEAR TERM...MAS/SAM SHORT TERM...SAM LONG TERM...AJZ AVIATION...JDM/JEF MARINE...AJZ CLIMATE...

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